in reply to SQL through perl is giving error

Why do you use eval and not check the return value of ->do?

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Re^2: SQL through perl is giving error
by ksublondie (Friar) on Aug 31, 2011 at 23:29 UTC
    Because I have 3 separate update and/or insert statements per do, wanted to make sure all succeed, and wasn't sure exactly how the return value would account for all possible errors. From my testing, it looks like do returns only the last statement result rows.

    Now if I add a rollback before the 2nd eval: 

    warn $inventoryUpdate.$statement."\n";
eval{
  $result=$db->do($inventoryUpdate.$statement);
  warn "result1=$result\n";
};
if($@){
  warn "Can't update.  Trying insert.\n\n$inventoryInsert$statement";
  $db->rollback;
  eval{
    $result=$db->do($inventoryInsert.$statement);
    warn "result1=$result\n";
  };
  if ($@){
    warn "Aborted because $@";
    $db->rollback;
    return 0;
  }
}
$db->commit;

    [download]
    It works! Apparently, the rollback resets $@, but why is the $@ message different in the 2nd eval without the rollback?
[reply]
[d/l]
[select]

      You might try the trace features of DBI to see more of what is going on.

[reply]
        Suppose there is a table "mytable" with column col_pk as follows. 
        col_pk
----
1
2
3

        [download]
        And update and insert sql as follows. 
        update mytable set col_pk=4 where col_pk=3;
insert into mytable (col_pk) values (3);

        [download]
        If you run the sql above only once, it never yields error. But if you run the sql twice, it will yield error because there is already 4 in mytable.

        I'm not sure. Just guessing.
[reply]
[d/l]
[select]

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